At the end of the 1800s, the Danish King, Christian IX and his wife, Queen Louise, married their six children into the dominating European royal families and Christian IX became known as "Europe's Father-In-Law". Today, his descendants are to be found all over Europe.These are their stories, stories of power, love, triumph, tragedy and honour, recounted through interviews and never before published letters, photographs and home movie footage, by over 30 members of the European royal family.